Developing a Simple Windows Application phần 2

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// // Required for Windows Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // } ///

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// // Required for Windows Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // } /// /// Clean up any resources being used. /// protected override void Dispose(bool disposing) { if(disposing) { if (components != null) { components.Dispose(); } } base.Dispose(disposing); } #region Windows Form Designer generated code /// /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// private void InitializeComponent() { this.myLabel = new System.Windows.Forms.Label(); this.myButton = new System.Windows.Forms.Button(); this.SuspendLayout(); // // myLabel // this.myLabel.Location = new System.Drawing.Point(8, 8); this.myLabel.Name = "myLabel"; this.myLabel.Size = new System.Drawing.Size(288, 184); this.myLabel.TabIndex = 0; this.myLabel.Text = "label1";
// // myButton // this.myButton.Location = new System.Drawing.Point(120, 200); this.myButton.Name = "myButton"; this.myButton.Size = new System.Drawing.Size(72, 24); this.myButton.TabIndex = 1; this.myButton.Text = "Press Me!"; this.myButton.Click += new System.EventHandler(this.myButton_Click); // // Form1 // this.AutoScaleBaseSize = new System.Drawing.Size(5, 13); this.ClientSize = new System.Drawing.Size(304, 237); this.Controls.AddRange(new System.Windows.Forms.Control[] { this.myButton, this.myLabel}); this.Name = "Form1"; this.Text = "My Form"; this.ResumeLayout(false); } #endregion /// /// The main entry point for the application. /// [STAThread] static void Main() { Application.Run(new Form1()); } private void myButton_Click(object sender, System.EventArgs e) { myLabel.Text = "Is this a dagger which I see before me,\n" + "The handle toward my hand? Come, let me clutch thee.\n" + "I have thee not, and yet I see thee still.\n" + "Art thou not, fatal vision, sensible\n" + "To feeling as to sight? or art thou but\n" + "A dagger of the mind, a false creation,\n" + "Proceeding from the heat-oppressed brain?";
} } } As you can see, the Form1 class is derived from the System.Windows.Forms.Form class. The Form class represents a Windows form. Note The System.Windows.Forms namespace contains the various classes for creating Windows applications. Most of the classes in this namespace are derived from the System.Windows.Forms.Control class; this class provides the basic functionality for the controls you can place on a form. The Form1 class declares two private objects named myLabel and myButton, which are the label and button controls you added to your form earlier. Because the myLabel and myButton objects are private, this means that they are accessible only in the Form1 class. Access modifiers enable you to specify the degree to which a class member is available outside the class. You can also use an access modifier to specify the degree to which the class itself is available. Table 6.1 shows the access modifiers in decreasing order of availability: public is the most accessible, and private the least. Table 6.1: ACCESS MODIFIERS ACCESS ACCESSIBILITY MODIFIER public Member accessible without restriction. protected internal Member accessible only within the class, a derived class, or class in the same program (or assembly). internal Member accessible only within the class or class in the same program (or assembly). protected Member accessible only within the class or derived classes. private Member accessible only within the class. This is the default. The Form1 class constructor calls the InitializeComponent() method. This method adds myLabel and myButton to the form and sets the properties for those objects. These properties include the Location (the position in the form), Name, Size, TabIndex (the
order in which the control is accessed using the Tab key), and Text. For example, the following code sets the properties of myLabel: this.myLabel.Location = new System.Drawing.Point(8, 8); this.myLabel.Name = "myLabel"; this.myLabel.Size = new System.Drawing.Size(288, 184); this.myLabel.TabIndex = 0; this.myLabel.Text = "label1"; You'll notice that the InitializeComponent() method is within #region and #endregion preprocessor directives. These directives enclose an area of code that may be hidden in VS .NET's code editor, leaving only the text that immediately follows #region visible. Figure 6.5 shows how the hidden code appears in VS .NET. Figure 6.5: Hiding code in VS .NET using the #region directive To view hidden code, all you have to do is to click the plus icon to the left of the code. Figure 6.6 shows the code within the #region and #endregion directives.
Figure 6.6: Viewing hidden code in VS .NET The Main() method runs the form by calling the Application.Run() method. The Application class is static and provides a number of methods you can use in your Windows programs. Because this class is static, you don't create an instance of this class, and its members are always available within your form. When the Run() method is called, your form waits for events from the mouse and keyboard. One example of an event is the clicking of the button in your form. The myButton_Click() method is the method you modified earlier that sets the Text property of myLabel to a string containing the quote from Macbeth. When myButton is clicked, the myButton_Click() method is called and the text in myLabel is changed; you saw this when you ran your form earlier. In the next section, you'll learn about the VS .NET Solution Explorer. Working with the Solution Explorer You can use the VS .NET Solution Explorer to view the items in your project, such as the namespace for your project. Of course, a project may contain more than one namespace. To view the Solution Explorer, you select View ➣ Solution Explorer. Tip You can also view the Solution Explorer by pressing Ctrl+Alt+L on your keyboard. You can use Solution Explorer to view the following items in a project's namespace: • References References include other namespaces and classes to which your form's code refers. You can employ the using statement to reference other namespaces and classes. • Icon File An icon file has the extension .ico. You use an icon file to set the image displayed in Windows Explorer for your application.
• Assembly File An assembly file contains the metadata for your application's assembly. An assembly is collection of code for your application. • Code Files A code file is a program source file, such as the code for a form. You saw an example of this in the earlier "Examining the Code behind the Form" section. Figure 6.7 shows the Solution Explorer for this example. Figure 6.7: The Solution Explorer As you can see from Figure 6.7, you can expand or collapse the items shown in the Solution Explorer by clicking the plus or minus icon, respectively. You can also display the properties for an item in Solution Explorer: When you have the Properties window displayed, selecting an item in Solution Explorer will also display the properties for that item. For example, in Figure 6.7, the properties for the MyWindowsApplication project are displayed; you can see that the project file is MyWindowsApplication.csproj. In the next section, you'll learn about the VS .NET Class View. Working with the Class View You use the VS .NET Class View to examine the classes, methods, and objects in your project. To see the Class View, you select View ➣ Class View. Tip You can also see the Class View by pressing Ctrl+Shift+C on your keyboard. Figure 6.8 shows the Class View for the example.
Figure 6.8: The Class View As you can see from Figure 6.8, you can view the classes, methods, and objects for the example. You can also view the properties for a selected item in the Properties window. For example, Figure 6.8 also shows the properties for the Form1 class. Next, you'll be introduced to the other types of Windows controls.